A difficult surgical reconstruction problem usually occurring in severe brachial plexus injuries in humans is root avulsion. This type of nerve injury is regarded as a type of central nervous system (CNS) injury not amenable to surgery (Carlstedt et al., 1995, Lancet 346: 1323-1325; Carlstedt et al., J Neurosurg 82(4): 661-663). The divided rootlets at the point of connection with the spinal cord, i.e., the ventral entry zone (VREZ) and the dorsal rootlet entry zone (DREZ), may withdraw to a large extent (before the decision to operate has been made several weeks after the injury), making direct repair by repositioning difficult (Narakas, 1987, Orthopade 16(1): 81-86). Many previous studies (in humans, non-human prima and other mammals) show that sectioned peripheral axons of one never can regenerate through foreign nerves to reinnervation different motor of sensory fields. In 1961, Seddon reinnervated the biceps and the brachialis muscles by anastomosing the distal part of the musculocutaneous nerve with the second, third and fourth intercostals nerves (Yeoman and Seddon, 1961, J Bone Joint Surg 43B: 493.499). In addition, nerve transfer, which is called as “neurotization” with interostals or other nerves, including spinal accessory nerves and anterior nerves of the cervical plexus, has also been reported to lead to some positive clinical results (Kotani et al., 1972, Excerpta Med Int 12th Congress Series 291: 348-350; Brunelli and Brunelli, 1980, In Surg 65(6): 529-531). However, these types of surgeries were still in experimental phase and suffered from lack of fundamental knowledge (Narakas 1987). Neither of the above-mentioned reports demonstrated a functional recovery of the treatment of root avulsion.
Recently, direct reconstruction of connectivity between the spinal cord and the nerves after spinal nerve root injury has also been demonstrated (Cullheim et al., 1989, Neuroscience 29: 725-733; Carlstedt et al., 1990, Restor Neurol Neurosci 1: 289-295; Carlstedt et al., 1993, J Neurol Neurosurg Psychiatry 56: 649-654; Smith and Kodema, 1991, Brain res Bull 30: 447-451). This kind of approach is more capable to bring the reconstructed neural networks close to the original statues. However, is clinical practice, it is difficult to find and approximate the retracted ends of the avulsed roots within 2-3 months after the injury, which is the minimum time period necessary to verify a real neurotemesis (Leffert, 1983, Schmidek H H, Sweet W H, eds. Operative Neurosurgical Techniques. Orlando: Grune & Stratton, 1495-1540). In most cases, this fact hinders the attempt to reinsert the avulsed roots to the spinal cord. However, there is no evidence showing that long-term regeneration supporting wrist or hand functions has been established. A repair of complete transection of the spinal cord in rats with a fibrin glue containing acidic fibroblast growth factor (aFGF) has been reported (Chang et al., 1996, Science 273: 510-513). However, no successful treatment for avulsion of nerve roots at their junction with the spinal cord has been reported.
In view of the above, new and effective strategies for repairing nerve root avulsion are desired.